The pulmonary artery is an artery that carries blood in the body from the right ventricle to the lungs in order to supply oxygen, and pulmonary arterial hypertension is defined as when the mean pulmonary artery pressure at rest is 25 mmHg or greater or when the mean pulmonary artery pressure during exercise is 30 mmHg. Pulmonary arterial hypertension is classified into “primary pulmonary arterial hypertension”, which is the case where no specific cause has been disclosed, and specific disease “associated pulmonary arterial hypertension”, which occurs secondarily due to a specific causative disease. Examples of the latter case include familial pulmonary arterial hypertension related to heredity, and the specific disease-associated pulmonary arterial hypertension may be caused by collagen vascular diseases (e.g., systemic sclerosis, systemic lupus erythematosus, etc.), portal hypertension, HIV infection, congenital heart diseases, and drugs or toxins such as an appetite suppressant or cocaine. Specific disease-associated pulmonary arterial hypertension is not significantly different from primary pulmonary arterial hypertension in terms of spontaneous progression, histopathological findings, response to treatment, etc. Primary pulmonary arterial hypertension is 1.7 times more common in women than in men and may occur in all ages, but it is frequent in those in their 20s and 30s. Approximately 7% of patients have a family history of mutation in the gene called BMPR2, by which the autosomal dominant trait appears to be inherited.
Patients with pulmonary arterial hypertension may present with symptoms such as shortness of breath (dyspnea), fainting, dizziness, peripheral edema (e.g., lower extremity edema), impotent feeling, anepithymia, increased heart rate, headache, precordialgia, cyanoderma, etc. Further, it may be accompanied by Raynaud's phenomenon, in which the fingers and toes easily become cold and turn blue. Patients with pulmonary arterial hypertension are often initially exposed to misdiagnosis such as influences from asthma or excessive stress, resulting in breathing difficulties; and after an average of 2.5 years, the patients are diagnosed correctly.
For the treatment of pulmonary arterial hypertension, surgical intervention such as interventional atrial septostomy, lung transplantation, heart-lung transplantation, etc. can be performed, but drug treatment is preferred because of the high cost and risk of surgical intervention. Currently, there are methods to use a general vasodilator as a drug for treating pulmonary arterial hypertension, but most vasodilators are calcium channel blockers, which are difficult to apply because they often do not show a significant effect on pulmonary arterial hypertension and have side effects associated with administration. Therefore, it is necessary to discover an effective therapeutic agent for pulmonary arterial hypertension.